[RE-wrenches] Sunpower off grid?

[Isaac Opalinsky]

Ray,

Please contact me off list to verify for these specific.  If you have the exact model number or a picture of the nameplate, I can help you verify whether they need to be positively grounded or not.

Most modules produced after 2012 can be installed in positive or negative grounded configurations, or in ungrounded configurations, and most of these modules will have the statement "Suitable for ungrounded, positive or negative grounded DC systems" on the module nameplate.  But especially if your customer got this product from an unauthorized source, you should verify.

As a rule, and going forward, there are no restrictions on grounding configurations with SunPower modules, and I don't think it's any big secret that SunPower is now one of many companies getting into energy management and backup power solutions.  While it might not be very easy to design with our modules for 12, 24 or 48V systems without a relatively high voltage MPPT controller, I haven't encountered any complications with the higher voltage controllers or AC coupling, of course.

Cheers,

Isaac Opalinsky | Technical Trainer | SunPower Corporation
Desk 443-569-3476 | Cell 443-277-6286


-----Original Message-----
From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Ray Walters
Sent: Thursday, August 21, 2014 12:47 AM
To: RE-wrenches
Subject: [RE-wrenches] Sunpower off grid?

Greetings fellow Wrenches;

I have a customer that just purchased some Sunpower E20 -435 modules somehow from Ebay, and wants me to design a backup power system for him.
This system would be battery based and not be grid tied.  SO the question is: has Sunpower put to rest the positive grounding issue with these modules?
I would want to either use a negative ground system or go ungrounded, as the charge controllers and battery based inverter do not play well with a positive grounded system.
My idea is that I could run these modules at lower voltage, either all in parallel (85.6 Voc) or 2 in series (191 Voc) with Midnite Classic controllers, and that the whole surface polarization issue will be minimized at these lower voltages.
I know this came up before, and Sunpower basically said they would revoke their warranty for any battery based systems, (which is why I'm no longer a Sunpower dealer.... :) Don't the newer Sunpower modules no longer need positive ground, and if so, which models is this true for?  In this case, the warranty is already suspect, so that's not an issue.  It just has to work safely.

Thanks in advance for your help,

--
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

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